TU44J2 - is it possible?

[AndreasN 0]

Hi

 

I've been having some fun with a big Excel sheet of TU engine specifications, and I've come up with an unusual combination that I think should work. I call it the TU44J2:

 

TU3 alloy block (206.98mm deck height)

TU5 crank with 82mm throw

TU3 126.8mm connecting rods

TU24 pistons (38.8mm compression height)

TU*J2 head with 32.5cc chamber

 

This should bring the piston crowns up to around 1.2mm below where they are in a stock TU2j2, increasing chamber volume by 5cc.

But due to the higher capacity (1449cc), compression ratio remains almost unchanged at 10:1. A relatively modest skim could bring that up to perhaps 10.5 or 11, and would still leave better piston-to-valve clearance than in a stock TU2J2.

 

Rod/stroke ratio is a bit on the short side at 1.55, but that's still ever so slightly longer than in the TU24.

 

 

I already have a TU3 block and a TU2J2 head. I've never built or rebuilt an engine before, but I think this could be a fun, relatively inexpensive way to start. In fact I already have some cheap, second hand TU24 pistons and a TU5 crank on their way to me from a breaker's.

 

Has anybody tried this combination before? Google has turned up nothing - maybe I have overlooked some fatal flaw in my plan that has kept anyone else from attempting it?

 

The usual way of reaching 1449cc seems to be with the longer 133.6mm connecting rods and milled down TU2J2 pistons, but if my calculations are right you'd have to take something like 5mm off the pistons, and that seems like a lot.

The alternative would be to keep it at 1361cc, but then I'd need to up the compression ratio some other way - either with the unicorn TU3J2 pistons, longer rods and (slightly less) milled down pistons, expensive forged Wössners or a very heavy skim of the head. Neither option sounds very appealing to me, though if all else fails I'll probably go for the last method.

 

I'd love to hear the thoughts of the expert TU engine builders in this forum Thanks.

[205rallye_slo 0]

Hello.

Nice project, looks like you will not be first to do this.

If you search on google: tu3 with tu5 crank, you will get some result on this forum.

But info are not very detailed... maybe is so easy to put it together:)

 

The crankshaft need some rework, or fit directly in? Timebelt puley is same tu3/tu5? Flywheel?

Tu5 rods sems stronger, but in my opinion to long-you need to remove to much material?(126.8 vs 133.5mm, so you need to remove 6.7mm??+2.5mm to compensate biger stroke?

On other hand in one topic is writen that tu5 rods was used...

 

 

Edited September 16, 2024 by 205rallye_slo

[205rallye_slo 0]

 

 

Another think is that this motor will be even more undersquere that tu5 -which they claim to be lezy(not wiling to revolve).  Strok ratio tu24 1,02, tu3 0.96,  tu5 0.95, "tu4" 0,91

 

Edited September 17, 2024 by 205rallye_slo

[Arthur 13]

What is the goal? To get it under 1500cc? 

 

I made a hybrid ones, just the other way around. I've put a 106 1.4 xsi crank into a 106 1.6 rallye engine. Result 1490cc, 7.5 ish compression and iron block. But the goal was to have keep it in one piece with 1.5 bar turbo pressure. But it did result in a quite revy turbo engine. And it kept in one piece with approx. 225 bhp and 300 Nm. Same can't be said about the ma box though (-:

Edited September 17, 2024 by Arthur

[205rallye_slo 0]

Goal:

TU3 alloy is around 20kg lighter then iron tu5 -good for car handling.

Using tu24 head on TU3 no go becouse compresion ratio(to big head camber)- so i understad that lowering cilinders is a must(or fit expensive domed pistons).

With tu5 cranks sems just tu3 pistons need to be lowered(or reshape in domed)? (If other parts fit together without modification)

Question how this "75x82" is working comper original Tu2 tu3 and tu5...

[Arthur 13]

Well, everything can work I think. Sandy will know all about it. I've seen TU7 builds even with 75,5 x 92 racing engines on youtube. Personally I think the stroke is more important than the ration of stroke / bore. And 92 mm stoker can do 10 000 rpm. It's just how deep your pockets are.

 

A skimmed tu5 8v head on the tu3 might work as well but only with even more bore. Heads are quite different although they look the same. Look at the tu3s versus tu24. Same manifold bolt template, but the holes of tu24 are much bigger. TU5 8 v heads match inlets of tu24, but they will have too big bore for alu block. They will not work with 75 mm liners and head gasket. TU5 90bhp head for example has smaller bearing than tu5j2 and also different inlet valve angles. TU5 90 bhp head cannot get wild cams without bearing rebore. It's a puzzle

 

Some of my achieve:

 

Tu3m

 

TU3s

 

TU24

 

Edited September 17, 2024 by Arthur

[AndreasN 0]

The engine is intended for fast road/trackday use, so there's no displacement limit. I want it to be quick, but I don't need every last HP - and I'm running an MA gearbox, so I don't want massive amounts of torque either.

 

205rallye_slo is basically spot on regarding my goals. I'd prefer to keep the alloy block; if I was going to switch to iron I might as well go for a 1.6.

I also want a big valve head (TU24 or TU2J2/TU3J2/TU5J2; I happen to have a J2 head, so that's what I'll use).

 

And I'd like to keep it simple and cheap: Off-the-shelf parts whenever possible.

 

I've selected this combination because it seems to give me 10:1 compression ratio with a J2 head and an alloy block, using easily available parts with no modification required. The added displacement is just a side effect.

 

I've seen the other threads on this forum about 1449cc engines. But they all seem to use the 133.6 mm rods and machined-down pistons, which I'd like to avoid. Especially the 4.5-5.0 mm that you'd take off a TU2J2 piston for a 1449 engine. In that case I'd prefer to stick to the 1360 crank and "only" have to machine a couple mm off the pistons.

 

The undersquare nature doesn't worry me too much; even with 82mm stroke it should still take some revs, and it'll essentially make my gearbox shorter, which is nice  My thinking is that with a sharp cam, a big-valve head and a pair of twin-barrel carbs, it should be more than enough engine to make it fun.

 

It's a good question regarding the flywheel and cambelt pulley. I thought they would fit straight on the TU5 crank, but maybe that's not the case?

[Arthur 13]

I don't know about the rods. 

 

Tu5 head would not work with 75mm bore as far as I know. 

Tu3s carb inlet will not fit tu2, tu24 or tu5

What J2 head do you have? 

Are 106 1.3 rallye engines rare in Denmark? 

 

Edited September 17, 2024 by Arthur

[205rallye_slo 0]

Tu24 head on picture-is not tu24(if will be 106 rallye miss the iniectors hole, if will be 205 rally will have 5 screws for inlet monifold)

Looks normal tu1 or tu3 alloy or?

[AndreasN 0]

I don't know about the other TU5's, but the TU5J2 head should be the same as the TU3J2 and TU2J2, no? The cams differ, but the heads should have the same casting number AFAIK. And the head was already on the TU3 when I bought it, so it does fit. Compression was low, though, and the engine generally needs a refresh.

 

1.3 Rallye engines don't grow on trees here. Though I suppose a crankshaft would be enough; the pistons are easily available, even brand new from Aprotec, and the rods, blocks and liners are shared with the TU5 and TU3, respectively.

 

But the TU24 pistons are available from Aprotec as well, so if there are no insurmountable problems I think I'll continue down that road. If nothing else then for the fun of it.

 

(Side note: Has anyone tried the Aprotec pistons? They seem to be generally well regarded in the 2CV community, but that's a bit lower power... I'll see how my used pistons are when I get them, and I'll at least be able to see if they'd fit. But if their condition is bad, I might try to ask Aprotec if they could supply a kit with TU2J2 liners and TU24 pistons.)

Edited September 17, 2024 by AndreasN

[Arthur 13]

Well, I would build an 1360 with J2 head then. Seems the easiest to me. I've been thinking about this myself ones, but went for the tu5JPs with BE4 instead. The +30 kg is not really a problem if you ask me. 

 

Do you have the 106 1.4 xsi specs as well? (iron)(to compare).  Carbs on the j2 though would require a custom manifold though and ifso, I would take 36 mm mikuni vacuum carbs (e.g. suzuki bandit)

 

 

[AndreasN 0]

A 1360 with a J2 head would be fine, but how would you solve the compression problem? The easiest way would be to skim the hell out of the head, but that'd change the shape of the squish area as well, and I generally don't like it as a solution.

 

Otherwise it becomes even more complicated than what I'm planning, doesn't it? Longer rods, brand new pistons that then need to be machined down (which I can't do myself), ensuring clearances between valves and pistons... Whereas the TU44J2 should be pretty much like a standard rebuild, except for the mixing of parts.

[Arthur 13]

But what is a j2 head? I believe there a Tu2j2 and tu5j2 

Edited September 17, 2024 by Arthur

[AndreasN 0]

From what I've been able to find, including here on this forum, all the TU*J2 heads are the same. Same valve size, same 32.5cc combustion chamber. They came with different camshafts depending on the application, but that's the only difference I know of. That also means that one of the potential advantages of a larger bore 8v TU engine, the opportunity to use larger valves, is lost. Unless you modify the head, which i don't plan on doing.

 

 

 

If that isn't the case I'd love to know, but so far I've assumed that a J2 head is a J2 head. I don't know where mine came from - as I recall it just says "J2" on the back of it, but I'll take another look and see if there are other markings.

[205rallye_slo 0]

AndreasN monifold and carbs you already have?

[AndreasN 0]

Yes, sort of at least.

 

The engine came with a manifold and a pair of Solex ADDHE 40's. I think the manifold has been modified from some other engine, and I haven't checked the fit of the ports to the cylinder head. But if I can reuse it, I will.

 

I once gave the carbs a kitchen table overhaul. One odd thing is that they seemed to be missing the upper venturi or whatever it's called - the venturi tube right under the air filter. But it almost looked like they were never fitted, so I think it could have been a factory variation that they left them out for some reason. Not sure about that.

 

 

In any case, I think I might splurge on a set of second hand Weber DCOE 40's; they're a bit expensive, but much cheaper than a set of throttle bodies and a full fuel injection conversion. And unlike the Solexes, parts are plentiful - and there are places where they know them well, and can jet them on a rolling road for a reasonable price. I fear that rejetting the Solexes for a new engine configuration could become a massive headache.

 

In any case I'd prefer to keep it carbed. I like historic motorsports, I like the sound of a tuned carb engine, and I want that, practical or not 

[205rallye_slo 0]

Make some foto of monifold and carb.

Solex yes looks nobody like them, jeting looks also in my place imposible.

Solex vs Weber half price, but in the end I belive is cheaper use weber.

And AX Sport have solex, 205rallye Weber dcom.

[AndreasN 0]

I believe mine may have come from an AX Sport.

 

Jets can be bought online, but they're more expensive than for Webers. And I'd still need someone who knows what they're doing to jet them in.

Much easier to find someone who already has a full selection of Weber jets and knows how to select them!

 

I'm working now, but I'll see if I can snap some pictures in the weekend.

[Arthur 13]

I'm not sure about that j2=j2 claim. It's been years ago but I did have 106 xsi and tu5-8v heads years ago assuming from first glance they were the same. But they where not. I'm pretty sure I have read somewhere, on this forum even, that 78,5 bore 8v heads will not work on 75mm bore because the wet liners/gasket does not line up. Somewhere in a topic about 1400 16v built. For example 106 rallye head looks almost the same as 205 rallye, but the injector holes are obviously missing. 106 also has 30° inlet valve angles jet 7mm step, while 205 has 8mm stem. 

 

Therefore if above is correct, tu5j2 must be different then tu2j2. Basically the only thing I really know 100% sure is: assuming things are the same with PSA is not wise. 

 

You must 95% sure have an ax gt engine then. If that is the case, you almost have a 205 rallye engine. 

Edited September 18, 2024 by Arthur

[Arthur 13]

18 hours ago, 205rallye_slo said:

Tu24 head on picture-is not tu24(if will be 106 rallye miss the iniectors hole, if will be 205 rally will have 5 screws for inlet monifold)

Looks normal tu1 or tu3 alloy or?

Realy? This is not tu24?

[AndreasN 0]

Good point about not assuming anything. But the head was mounted on the engine when I bought it, and of all the problems I've had, head gasket leaks wasn't one. So whatever it's from it must work with the wet liners and 75 mm bores. There were also other 8V TU5's than the TU5J2. Could you have had one of them?

 

The 205 Rallye was a TU24: TU1 block with a 73.2 mm crank and very short conrods, right? And the TU24 head was distinct from the TU2J2 in the 106 Rallye S1.

 

The AX GT I think was a TU3S. Same block as mine (and the TU2J2), but with a slightly less wild head.

 

As it stands, I think my engine is closest to an alloy version of the TU3J2 in the 106 XSI 1.4. I'm just missing the taller pistons that would raise compression, and which seem to be very difficult to find. But the head, crank, conrods and block height should be the same. That doesn't help me much if I can't get the right pistons though

 

Hence my plans  for a "mix and match" TU44J2.

 

 

[AndreasN 0]

48 minutes ago, Arthur said:

Realy? This is not tu24?

It says "3S" on it. Wouldn't that mean that it's a TU3S head?

[Arthur 13]

Is the deck height obvious to see on above picture. Tu3 always having the high block? I believe there is also 2 cam belts. A short one and a long one for the same reason (deck height) meaning the high alu is equal to the iron block? Had to say unless yo have all deck heights, rod length and piston data of all tu engines. 

[205rallye_slo 0]

Arthur is always combination of 4 parts: block, rod, piston and crank.

So if you change one component you need to compensate with others. 

But in case using diferend head(with more volume of camber) you need to tale also this in acount.

Im just speak about theory, in next month i will open my tu3 alloy(not tu3s), tu24 head is on the way, and then i wil decide if i make experiment with tu5 crank(also avalible to pick up+rods), or just lower the head to get 5cc less chamber...or lower the block and liners+reshape pistons to domed... 

[Arthur 13]

Yeah, check the 106 xsi pistons as well. If I remember correctly, they are domed versions of the alu tu3 block pistons.

Edited September 19, 2024 by Arthur